The present invention is directed generally to devices that can be inserted into the body in place of damaged bone tissue to provide underlying support for bone joints, without requiring complete or even partial replacement of the bone joint.
Endoprostheses have been commonly used to replace the damaged ball of the femur and/or the acetabular socket of the hip bone when these parts are damaged or deteriorate and do not properly function. In cancer-damaged hip bones, a portion of the pelvis (ilium) is attacked by cancer and is thus incapable of supporting the acetabulum in the usual manner. While a hip replacement is not necessitated due to failure of the femoral ball or the acetabulum, it is commonly performed in such a situation because there has been no way to preserve the acetabulum cup while removing the damaged tissue from the pelvis beneath, and supporting the natural acetabulum to withstand the forces to which it is commonly subject. The acetabulum cup has routinely been removed prior to tissue removal and completely replaced with an artificial prosthesis after removal of the damaged pelvic tissue below.
Heretofore, total hip prosthesis surgery has been performed wherein a cup is fitted in the acetabulum, and a femoral prosthesis member, which comprises a stem or shank portion and an artificial head, is fixed to the femur to provide a prosthetic hip joint. Subtotal hip replacement formerly necessitated by the above-described pelvic damage has involved removal and replacement of the acetabulum with a metal acetabular cup, wherein the metal cup provides a metal-surfaced socket for receiving the head of the femur.
Total and subtotal hip replacement is undesirable in cases of pelvic damage where the natural ball and socket of the hip joint is undamaged. A significant number of total or subtotal hip joint implants have failed by the acetabular prosthesis coming loose from its mount. A loose acetabulum prosthesis can erode bone in the direction of the applied forces during use, i.e., in the superior and posterior directions. This is particularly true where the loosened prosthesis had been implanted using bone cement, polymethylmethacrylate (PMMA), and/or screws and pins. This accelerated erosion shortens the life of the implant.
While the prior art has addressed improvements in the field of bone joint replacement, it has not addressed the problem of unnecessarily removing healthy bone joints only because the support structure under the bone joint was diseased or damaged. For example, U.S. Pat. No. 5,326,367 to Robioneck discloses an endoprostheses for a cancer-damaged pelvis. The endoprostheses comprises distal and proximal parts that can be screwed together, and include mounting extensions to be screwed to the hip bone, or alternatively, to a vertebra. However, while Robioneck discloses a potentially viable device and method to implant a prosthesis in a damaged pelvis, it does not address the issue of how to support the bone joint without replacing it with an artificial prosthesis.
Consequently, there is a need for joint preservation rather than routine joint removal and replacement when only a portion of the pelvic bone is destroyed. Thus, a need exists for a device that can be inserted into the body in place of damaged bone tissue that provide underlying support for bone joints, preempting the requirement for complete or partial replacement of the bone joint, and methods for inserting such devices. Furthermore, the following device and method is likewise suitable for other joints within the human body.
It is a primary object of the present invention, therefore, to overcome the disadvantages of the prior art and provide a durable, reliable spacing device that can support a joint in a damaged bone so that replacement of the joint is not required.
It is a further object of the present invention to provide a method to implant such a spacing device.
A further object of the present invention is to reduce surgical time for the removal of damaged bone tissue adjacent to a joint previously requiring complete reconstruction of the socket portion of the joint.
A still further object of the present invention is to reduce blood loss by up to 80% over prior procedures by incorporating the above-noted surgical procedure in place of previously partial or full bone joint reconstruction. Additionally, surgical time and surgical complexity are significantly reduced.
Yet another object of the present invention is to decrease a patient""s rehabilitation time by eliminating the necessity of partial or full bone joint reconstruction when removing diseased bone tissue adjacent to a joint.
The aforesaid objects are achieved by providing a spacing device for supporting a bone joint adjacent diseased or missing bone tissue, comprising a rigid support having a contoured surface and a semi-resilient pad. The pad is shaped to cradle and support the healthy bone joint and may promote bone integration. The reverse side of the pad is fixedly connected to one end of the contoured support piece. The other end of the contoured support piece is shaped to straddle healthy bone tissue adjacent the damaged area, such as the ilium in the case of a hip joint and is to be fixedly connected to the adjacent healthy tissue, using suitable means, such as biocompatible Steinman pins and polymethylmethacrylate (PMMA, bone cement). Other configurations of the support piece can be utilized depending on the joint needing support.
The result is that the diseased, damaged, or necrotic tissue can be removed without requiring removal of the natural bone joint. Because the undamaged bone joint is not replaced, the problems commonly experienced during an following bone joint replacement are avoided. In particular, blood loss during surgery, surgical cost, surgical time, and rehabilitation of the patient after surgery is reduced.
Other objects and advantages of the present invention will become apparent from the following detailed description when read in the light of the several figures.